Mrs Spence retired from the force in 2010 after serving 32 years – “when I had completed my 30 years I didn’t feel it was the right time to go”- having started life as a teacher before becoming a police officer.

For the past two years she has been a non-executive director at the trust and will take over as chairman next month.

The trust provides mental health, learning disability, children’s and social care services to around 750,000 people living in Cambridgeshire and Peterborough. It has 50 sites across the county and employs around 2,200 staff and has an annual income of £150million.

She succeeds David Edwards, who has stepped down after two years as chairman.

Mrs Spence said: “He will be a hard act to follow but I am confident I can continue his good work to ensure success.

“I am passionate about putting the citizen, the patient, and the service user at the very centre of everything we do.

“We have a really good strategy in place going forward and, together, we can make a difference.”

Chief executive Aidan Thomas said: “Julie is the ideal person to lead this trust in what is an extremely challenging time for not just this trust, but the whole NHS.”

“We’d also like to pay tribute to David Edwards, who has stepped down after a successful term as chairman. David has worked in the NHS for more than 50 years and has been an outstanding leader of the board. We wish him well for the future.”

The chairman’s vacancy was first advertised last month and a short list drawn up prior to final interviews on Tuesday.